Renormalization of the energy spectrum of quantum dots under vibrational resonance conditions: Persistent hole burning spectroscopy

A theory of photophysical burning of spectral holes in an inhomogeneously broadened light absorption profile of spherical quantum dots under vibrational resonance conditions is developed. The energy spectrum and the eigenfunctions of polaron-like excitations that arise in a quantum dot when the energy of an optical phonon is close to the energy gap between some pair of levels of the quantum dot electron subsystem are found by the method of canonical transformations. Expressions describing the difference light absorption spectra of quantum dots in the regimes of strong and weak confinement are obtained within a simple kinetic model.     

The theory and experiment of solute migration caused by excited state absorptions

Nonsymmetrical transition from reverse-saturable absorption (RSA) to saturable absorption (SA) caused by excited state absorption induced mass transport of the CuPcTs dissolved in dimethyl sulfoxide is observed in an open aperture Z-scan experiment with a 21-ps laser pulse. The nonsymmetrical transition from RSA to SA is ascribed neither to saturation of excited state absorption nor to thermal induced mass transport, the so-called Soret effect. In our consideration, strong nonlinear absorption causes the rapid accumulation of the non-uniform kinetic energy of the solute molecules. The non-uniform kinetic field in turn causes the migration of the solute molecules. Additionally, an energy-gradient-induced mass transport theory is presented to interpret the experimental results, and the theoretical calculations are also taken to fit our experimental results.     

On the fluid-loaded thin-panel absorbers

The sound absorption of fluid-loaded thin-panel absorbers was investigated. A general theory and an approximate theory are given. Parameters of potential energy kinetic energy, and the fluid-loading factor are proposed. This has made the absorption mechanism clearer, and the computation simpler than before. The absorption coefficients and impedances of thin-panel absorbers were tested with a hydro-acoustical tube. The experimental results agreed well with the theoretical results.     

On the magnetic dipole absorption of electromagnetic radiation by a fine conducting particle

The cross section of absorption of electromagnetic radiation by a fine spherical conducting particle is estimated in terms of the classical kinetic theory of electrical conduction. The mixed diffuse-specular mechanism of charge carrier reflection from the sample boundary is considered. A correlation between the coefficient of specular reflection and the absorption cross section at different temperatures is analyzed.     

Kinetic model for a step edge in epitaxial growth

A kinetic theory is formulated for the velocity of a step edge in epitaxial growth. The formulation involves kinetic, mean-field equations for the density of kinks and "edge adatoms" along the step edge. Equilibrium and kinetic steady states, corresponding to zero and nonzero deposition flux, respectively, are derived for a periodic sequence of step edges. The theoretical results are compared to results from kinetic Monte Carlo (KMC) simulations of a simple solid-on-solid model, and excellent agreement is obtained. This theory provides a starting point for modeling the growth of two-dimensional islands in molecular-beam epitaxy through motion of their boundaries, as an alternative to KMC simulations.     

Kinetic equations for dense fluids

It is demonstrated that the kinetic equation of Davis's effective potential theory follows directly from the application of well-defined approximations to the three-body correlations involved in the second equation of the BBGKY hierarchy. The same, simple mathematical techniques involved in this demonstration are used to derive two other kinetic equations, one of which is a generalization to high densities of the Boltzmann equation. In order to facilitate its application to the calculation of the van Hove and other correlation functions, the kinetic equation of the effective potential theory is Fourier-Laplace transformed: explicit formulae are given for the matrix elements of all operators that occur in this equation.     

Magnetic relaxation in a spin-1 Ising model near the second-order phase transition point

The magnetic relaxation of a spin-1 Ising model with bilinear and biquadratic interactions is formulated within the framework of statistical equilibrium theory and the thermodynamics of irreversible processes. Using a molecular-field expression for the magnetic Gibbs energy, the magnetic Gibbs energy produced in the irreversible process is calculated and time derivatives of the dipolar and quadrupolar order parameters are treated as fluxes conjugate to their appropriate generalized forces in the sense of Onsager theory. The kinetic equations are obtained by introducing kinetic coefficients that satisfy the Onsager relation. By solving these equations an expression is derived for the dynamic or complex magnetic susceptibility. From the real and imaginary parts of this expression, magnetic dispersion and absorption factor are calculated and analyzed near the second-order phase transition.     

反饱和特性化合物锌四苯并卟吩巴豆酸苯氧树脂的光吸收谱测定

报道一种新型的有机材料锌—四苯并叶吩—巴豆酸—苯氧树脂(缩写为Zntbp—CA—PhR)体系薄膜样品的吸收谱的测定，及其主要吸收谱带在激光作用下的变化情况及动力学过程。实验观察到此种材料显著的饱和及反饱和吸收现象，并观察到它的再反饱和过程，定性分析了变化过程中的物理机制。这种特征在可见光波段一个较宽的区域内都会出现。所获结果为此种有机材料在光谱域信息存储和光学限制等方面的应用提供了理论和实验依据。     

On the negative longitudinal magnetoresistance for a thin wire

A simple kinetic theory is described for the negative longitudinal magnetoresistance of a thin wire.     

Simple theory of protein folding kinetics

We present a simple model of protein folding dynamics that captures key qualitative elements recently seen in all-atom simulations. The goals of this theory are to serve as a simple formalism for gaining deeper insight into the physical properties seen in detailed simulations as well as to serve as a model to easily compare why these simulations suggest a different kinetic mechanism than previous simple models. Specifically, we find that non-native contacts play a key role in determining the mechanism, which can shift dramatically as the energetic strength of non-native interactions is changed. For proteinlike non-native interactions, our model finds that the native state is a kinetic hub, connecting the strength of relevant interactions directly to the nature of folding kinetics.     

Diffusion in a 2D bond percolation model. A Monte Carlo simulation

A Monte Carlo computer simulation of a simple stochastic hopping model is presented. The velocity autocorrelation function and the diffusion coefficient are analyzed and compared with the results obtained by using kinetic theory. The theory and the simulation agree within the statistical error.     

Diagrammatic techniques in the Martin-Schwinger-Puff many-body theory

In an attempt to understand the connection between the Martin-Schwinger-Puff Green's function approach to the many-body problem and the diagrammatic approach of Brueckner and Goldstone, the perturbation expansion of the Green's function theory is studied. This expansion leads naturally to a representation of the theory by two sets of time-dependent diagrams—the kinetic energy diagrams and the potential energy diagrams. Rules are given for writing each time-dependent diagram as a sum of time-independent diagrams. Complications arise in the application of these rules to bubble diagrams. A special simple treatment of these diagrams is then proposed. There exists a simple relation between families of kinetic diagrams and potential diagrams. This relation stems from a rather general thermodynamic identity. Both the relation and its thermodynamic origin are described. As a consequence of these studies, some connections between the Brueckner-Goldstone theory and the Green's function theory are made.     

催化动力学光度法测定痕量铜的研究进展

本文探讨和论述了近年来催化动力学光度法测定痕量铜的研究进展，比较了催化光度法与原子吸收法、萃取光度法的优缺点；介绍了催化动力学光度法的原理；评述了催化褪色光度法、催化显色光度法、催化荧光光度法等的研究进展，探讨和展望了催化动力学光度法未来的研究方向和发展前景，包括：1．对传统显色剂改性或合成新的高灵敏度、高选择性显色剂；2．活性剂增敏研究；3．加强相关催化机理的研究和探讨。全文参考文献29篇。     

Novel Kinetic Theory of the Classical Isotropic Oscillator Gas, the Flexible Shell Model

Ever since Chapman and Enskog first used the hard sphere model to evaluate the collision integral in the Boltzmann equation, more sophisticated models for molecular encounters have been sought. Rotation of molecules in kinetic theory has been pursued with a number of models, such as the spherocylinder or loaded sphere, to account for that aspect. As these efforts continued, more workers started to incorporate quantum mechanics methods in pursuit of solutions to the Boltzmann equation. Progress there with both rotational and vibrational features of molecules has been attained. Until now though, there has been no classical vibration model for molecules in kinetic theory. Far from standard kinetic theory, here a simple classical mechanics isotropic oscillator is combined, through a flexible shell, with the hard sphere model in a full Chapman Enskog procedure. The intent here has been to introduce the model, so items like translational-vibrational coupling have not been included. Still, the results compliment literature.     

Lyapunov spectrum of a random Lorentz gas in a magnetic field

The Lyapunov exponents and the Kolmogorov Sinai entropy for 2- and 3-dimensional, dilute, random Lorentz gases in a magnetic field are calculated. The results are obtained by combining simple kinetic theory with geometric methods from dynamical systems theory. The Lyapunov exponents are explicitly calculated up to second order in the magnetic field.     

Dust in the Universe – Similarities and Differences,by K.S. Krishna Swamy

A simple microscopic deduction of Archimedes' principle as applied to gases is given in terms of the kinetic theory, and some conventional explanations of barometric effects are queried.     

Theory of sound absorption in heterogeneous dielectric with an admixture of magnetic nanoparticles

A general theory of sound wave absorption in heterogeneous crystalline structures is proposed using the quasi-classical kinetic equation (QKE), and the microscopic dependence of sound wave damping is calculated: γ(ω, ξ*), where ω is the frequency of external sound as a fumction of concentration ξ* of ferromagnetic particles over a wide range of their average diameters (from centimeter to nanoscale).     

Ein kinetisches Modell für Grundgrößen der Stabilitätstheorie stationärer Zustände

A simple kinetic model which can be solved exactly is used to discuss some basic quantities in the stability theory of stationary states. In particular one microscopic and two phenomenological gains of information are introduced and compared. In addition several other properties of the theory can be illustrated.     

Hydrodynamics from kinetic models of conservative economies

In this paper, we introduce and discuss the passage to hydrodynamic equations for kinetic models of conservative economies, in which the density of wealth depends on additional parameters, like the propensity to invest. As in kinetic theory of rarefied gases, the closure depends on the knowledge of the homogeneous steady wealth distribution (the Maxwellian) of the underlying kinetic model. The collision operator used here is the Fokker-Planck operator introduced by J.P. Bouchaud and M. Mezard [Wealth condensation in a simple model of economy, Physica A 282 (2000) 536-545], which has been recently obtained in a suitable asymptotic of a Boltzmann-like model involving both exchanges between agents and speculative trading by S. Cordier, L. Pareschi and one of the authors [S. Cordier, L. Pareschi, G. Toscani, On a kinetic model for a simple market economy, J. Stat. Phys. 120 (2005) 253-277]. Numerical simulations on the fluid equations are then proposed and analyzed for various laws of variation of the propensity.     

Anisotropy in Borrmann spectroscopy

In this paper we introduce Borrmann Spectroscopy as a method for measuring X-ray absorption spectra under conditions of an exotic wave field, namely, a coherent superposition of two plane waves. The essential features of the Borrmann Effect (also known as anomalous transmission) are outlined. We show that the Borrmann Effect can lead to a very strong relative enhancement of quadrupole absorption. After describing some early results in this field, and some general considerations of multiple-wave absorption, we contrast recent results on anisotropy in Borrmann spectroscopy with normal absorption. Despite the qualitative success of a simple model for quadrupole enhancement, temperature dependence and anisotropy, a general theory of the Borrmann Effect is required which includes anisotropic and non-dipolar scattering. We outline some first steps towards such a theory.